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Flashcards · Biology · DNA and the Genome

Mutations and Non-coding DNA (Higher tier)

15 cards

  1. What is a mutation? (Higher tier)

    A change in the base sequence of DNA.

  2. How often do mutations occur? (Higher tier)

    Continuously.

  3. What do most mutations do to the protein? (Higher tier)

    Nothing, or they change it only slightly, so its function is not changed.

  4. What can a few mutations do to a protein? (Higher tier)

    Code for an altered protein with a different shape.

  5. What can happen to an enzyme with an altered shape? (Higher tier)

    The substrate may no longer fit its active site.

  6. What can happen to a structural protein with an altered shape? (Higher tier)

    It may lose its strength.

  7. What is a substitution? (Higher tier)

    One base is replaced by a different base.

  8. Why does a deletion usually have a bigger effect than a substitution? (Higher tier)

    It shifts the grouping of every triplet after it, so many amino acids can change.

  9. Do all parts of DNA code for proteins? (Higher tier)

    No.

  10. What can non-coding DNA do? (Higher tier)

    Switch genes on and off.

  11. How can a variant in non-coding DNA affect an organism? (Higher tier)

    It can alter how genes are expressed.

  12. How can a variant in coding DNA affect an organism? (Higher tier)

    It can alter the activity of a protein.

  13. What can cause mutations? (Higher tier)

    Chance errors when DNA is copied, ionising radiation and some chemicals.

  14. Can a mutation ever be beneficial? (Higher tier)

    Yes, very rarely, if the new phenotype suits the environment.

  15. A normal gene and a mutated gene, each making an enzyme, with no labels. Explain what has gone wrong in the bottom row. (Higher tier) The same diagram with the changed base, the different amino acid and the substrate that fits or does not fit labelled.

    One base has changed, so one amino acid is different. The protein folds into a different shape, so the substrate no longer fits the active site and the enzyme cannot work.